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Disk Utility fails when I try to partition external USB drives. This has happened on multiple SSD drives.
Disk Utility:
'Initialized /dev/rdisk4s2 as a 4 TB case-insensitive HFS Plus volume with a 327680k journal
Mounting disk
Creating a new empty APFS Container
Unmounting Volumes
Couldn't unmount disk. : (-69888)
Operation failed..."
MacBook Air, macOS 14.7
Not sure what is causing the error, but why are you partitioning an APFS drive. Just add Volumes.
You have three kernel extensions loaded. I don't know if they would cause the problem you are having with Disk Utility, but third-party kernel extensions will always cause problems eventually. If you really need to partition the drive, try starting up in Safe Mode and see if it works.
Make sure to use Disk Utility to erase the whole physical drive as described in this Apple article:
Erase and reformat a storage device in Disk Utility on Mac - Apple Support
Some drive manufacturers do some strange things with the partition table & file systems so it is always best to completely erase the drive yourself before using it for the first time.
Thank you Barney and HWTech. I've made progress and am nearing the end of the road.
This started with very slow performance on USB SSDs.
Partition and Erase in Disk Utility were failing.
I first partitioned the new SSDs to start at the lowest level.
I determined Disk Utility could not unmount the SSDs.
I booted in Safe Mode and the problem did not occur.
The SSD was still terribly slow.
I tried another SSD from the same vendor. Ditto.
I tried one from a different vendor. Fast!
Disk Utility still failed with a normal boot:
Do to not being able to unmount the SSDs.
Also, Carbon Copy Cloner could not unmount the SSDs.
I upgraded to Sequoia 15.1.
I removed all unsigned SW. No Major EtreCheck issues left.
Next step: A “Sterile Install”.
This is like moving house and jettisoning all the crap you no longer need.
I’ll only reattain Apple SW and a small number of necessary 3rd-party apps
that I’ll restore from their original sources. Only 10 apps and 2 utilities!
From Time Machine, I’ll restore the OS, Desktop, and Documents.
I made copies of the Applications and Utilities folders to keep a record of all the apps I had. I can restore anything else needed from original sources, a TM backup, or a Carbon Copy Cloner backup.
Sterile! Only Apple SW and a small number of necessary 3rd-party apps. Years of crap gone!
I’ll post back.
Disk Utility failed while partitioning a USB-SSD drive.
